NU 2014-102B

Primary Inventors

Franz Geiger*

Tom Miller* (CalTech)

Short Description

Metal nanofilms that convert gravitational energy to electrical energy when aqueous drops roll down their surface.

Background

Harvesting electrical energy from natural resources is critical to limit the consumption of batteries and fossil fuels. Approaches for electric power generation from nanoscale conducting or semiconducting layers in contact with moving droplets of aqueous solutions pose challenges regarding fabrication, scaling, and long-term stability during operation in in the field. To date, there is no marketed product for the generation of electrical energy from the motion of a fluid on a surface.

Abstract

Northwestern researchers have developed metal nanofilms, prepared by electron-beam physical vapor deposition, that convert gravitational energy to electrical energy when aqueous drops flow on their surfaces. Metal nanofilms, having an average thickness of ~10 nm, produce open-circuit potentials of several tens of millivolt and current densities of several microA per square cm, while thicker films, in the nanoscale range, produce ten times less voltage, indicating an optimum between film thickness and electron mean free path within the conductor is possible. The metal nanofilms were originally supported by glass, but other common materials may be adopted such as plastic sheets, which are also flexible. The invention enhances flow-induced power generation by adopting inexpensive and commonly available materials. The high purity of the metal nanofilm prevents further growth of the oxide nano-overlayer, resulting in its superior stability when compared to other approaches.

Applications

• Electrical power generation in vertical slanted building surfaces, marine environments, estuaries
• Directional sensing of liquid flow

Advantages

• Offers a robust and durable process for the generation of electrical current
• Employs inexpensive and commonly available material
• Offers cost-efficient alternative for electric power generation from nanoscale conducting or semiconducting layers

IP Status

Issued US Patent No. 9,738,966. 

Additional US and International applications have been filed. 

CalTech shares in one PCT filing.

Publication

Boamah M, Lozier E, Kim J, Ohno P, Walker C, Miller T and Geiger F (2019) Energy Conversion via Metal Nanolayers. PNAS.  116: 16210-16215.

Metal nanofilms with oxide nano-overlayers for gravitational to electrical energy conversion.